建造者模式將一個複雜物件的建立和它的表示分離，使用同樣的建立過程可以建立不同的表示

應用例項

在Java中，建造者模式是一種常見的設計模式，StringBuilder以及okhttp3.Request都應用了建造者模式：

OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
        .url("http://www.baidu.com")
        .build();

實現

我們將要實現一個Human類的建造者模式實現。

首先建立Human類

public  class Human {
    private String name; private int age; private int weight; private int height; //-----------Setter and Getter-------------------- public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public int getWeight() { return weight; } public void setWeight(int weight) { this.weight = weight; } public int getHeight() { return height; } public void setHeight(int height) { this.height = height; } //-----------Setter and Getter-------------------- @Override public String toString(){ return getName() + " 的年齡是 " + getAge() + " 的體重是 " + getWeight() + " 的身高是 " +getHeight(); } } 
 

建立Builder介面

public interface Builder {
    Builder setAge(int age); Builder setName(String name); Builder setWeight(int weight); Builder setHeight(int height); Human build(); } 

建立ConcreteBuilder類，使用這個類可以構建Human物件

public class ConcreteBuilder implements Builder { private Human human; @Override public Builder setAge(int age) { this.human.setAge(age); return this; } @Override public Builder setName(String name) { this.human.setName(name); return this; } @Override public Builder setWeight(int weight) { this.human.setWeight(weight); return this; } @Override public Builder setHeight(int height) { this.human.setHeight(height); return this; } @Override public Human build() { return this.human; } public ConcreteBuilder(){ this.human = new Human(); } } 
 

使用演示

public class BuilderDemo {
    public static void main(String[] args){ Human human = new ConcreteBuilder() .setAge(21) .setName("Amos") .setHeight(176) .setWeight(130) .build(); System.out.println(human); } } 

它的輸出為：

Amos  的年齡是  21  的體重是  130  的身高是 176